This is a new TNT cannon and turret design that works in 1.7.x as well as 1.8, so you can use it on your ship designs and you won't have to modify them when Movecraft for 1.8 comes out.

In 1.7.x it functions much as previous turrets have. In 1.8 it gains the ability to control the guns elevation to allow direct fire, or a high lobbing arcs as required.

Also included is a Silver Empire Light Cruiser which uses this new weapon as its main armament.

Both are next to a firing range, which you can use for testing or modifying the design to suit your needs.